Battery Faults and Its Reasons


Manifestation of Battery Faults

The faults of lead-acid battery can be divided into external faults and internal faults according to their parts.

1)External faults:

Shell fracture, pole pile corrosion, pole pile looseness and sealant dry crack.

2)Internal faults:

Plate vulcanization, self-discharge, plate short circuit, active material shedding, plate grid corrosion and plate arching.

Common internal failures of lead-acid batteries

Failure phenomena of Plate vulcanization are as followed:

1) Battery capacity decreased with high rate discharge meter detection and single cell voltage rapidly decreased.

2) The electrolyte density drops below the specified normal value.

3) The battery voltage is too high at the beginning and the end of charging, up to more than 2.7V.

4) The battery produces bubbles too early when charging, and even there are bubbles at the beginning of charging.

5) The electrolyte temperature rises too fast when the battery is charged, which is easy to exceed 45℃.

6) Battery discharge voltage drop too fast (with low discharge rate discharge), and prematurely dropped to the termination voltage.

7) Hard and insoluble large white particles are generated on the plate.

Fault cause:

1) The battery is placed in the state of discharge and half discharge for a long time. Due to the large temperature difference between day and night in lead sulfate, two opposite processes of dissolution and crystallization occur alternately in the electrolyte constantly, and recrystallization is generated. After repeated recrystallization, thick and insoluble lead sulfate grains are formed on the plate.

2) The battery often excessive discharge or small current deep discharge, so as to generate lead sulfate in the inner layer of the plate fine pores, usually charging is not easy to recover.

3) The electrolyte level is too low, and the active substances on the top of the plate are exposed to the air and oxidized. The fluctuation of the electrolyte makes it contact with the oxidized active substances when the car is driving, and the coarse-grain lead sulfate is generated.

4) The initial charging is not complete or periodic replenishment is not performed. The initial charge of the battery is not complete or during the use of periodic replenishment, so that it in the state of semi-charge for a long time to use, the discharge product of lead sulfate on the plate for a long time to exist, but also through the relysis of the formation of coarse particles.

5) Lead sulfate will be produced when the electrolyte is impure or the battery is discharged by itself due to other reasons, thus providing a material basis for recrystallization of lead sulfate.

Battery Bulge

We use the cell phone battery, use for a long time, some will appear bulge, but some do not. No matter what type of battery, bulge is common, including our UPS power supply, EPS power products used lead-acid batteries, also occur bulge. Blobs can have a big impact on battery use and can even cause an explosion hazard.

The swelling of lead-acid battery is mainly caused by the increase of pressure brush inside the body, which is mainly caused by the following reasons:

(1) The opening pressure of the relief valve is too high, or the relief valve is blocked. When the pressure inside the body increases to a certain level, the valve cannot be opened normally, in which case the bulge is bound to be deformed.

(2) When the floating charging pressure is set too high and the charging current is high, the oxygen precipitation on the positive electrode plate is accelerated without the time for recombination in the negative electrode. At the same time, the temperature in the battery rises rapidly. When the exhaust is not enough and the pressure reaches a certain level, the VRLA battery appears bulging deformation.

(3) During the charging operation of lead-acid battery, especially in the series battery pack, if the battery pack has been charged, the battery with poor quality will often have bad internal gas compounding and other phenomena, resulting in bulging.

(4) As the lead-acid battery is a liquid-deficient design, there is a reserved escape way for the combination of gases. However, if there is a “liquid-rich” phenomenon, it will prevent the generated oxygen from diffusing to the negative pole, reduce the compound rate of oxygen and increase the pressure inside the body.

In the process of our use, if we find that the lead acid battery is bulging, we should replace the bulging battery, so as not to affect the use of other batteries, or affect the use of the whole equipment.


The battery has a mild vulcanization fault, and can be charged for a long time with a small current of 2~3A, which is overcharge; Or use full discharge, full charge and discharge cycle method to reduce the active substance; It can also be eliminated by removing vulcanization and charging. Seriously vulcanized battery should be scrapped.

Share now

Leave a Reply

Your email address will not be published.